KR100480113B1 - Driving control apparatus and method for reciprocating compressor - Google Patents

Abstract

The present invention relates to an operation control apparatus and method for a reciprocating compressor, and detects the mid position of the current stroke and varies the stroke according to the mid position, thereby maintaining a constant TDC regardless of the load to improve system efficiency. will be. To this end, the present invention includes stroke estimating means for calculating a stroke estimate using a voltage and a current applied to a motor and a motor parameter; Mid position calculating means for calculating a mid position with said stroke estimate; Stroke command value determining means for comparing the mid position with a previous mid position to determine a stroke command value by adding or subtracting a stroke command correction value according to the stroke command value; And a stroke control means for comparing the stroke command value with the stroke estimation value and controlling the stroke by varying the voltage applied to the motor according to the comparison result.

Description

Operation Control System and Method of Reciprocating Compressor {DRIVING CONTROL APPARATUS AND METHOD FOR RECIPROCATING COMPRESSOR}

The present invention relates to an operation control apparatus and method for a reciprocating compressor, and detects the mid position of the current stroke and varies the stroke according to the mid position, thereby maintaining a constant TDC regardless of the load to improve system efficiency. The present invention relates to an operation control apparatus and a method of a reciprocating compressor.

1 is a block diagram showing a configuration of an operation control apparatus of a conventional reciprocating compressor, and as shown therein, a current detection unit 4 for detecting a motor current applied to a motor; A voltage detector (3) for detecting a motor voltage applied to the motor; A stroke estimator (5) for estimating a stroke based on the detected motor current, motor voltage and motor parameters; A comparator (1) for comparing the stroke estimate value with the stroke command value and outputting a difference signal accordingly; In accordance with the difference signal, a stroke controller 2 which controls the stroke by varying the voltage applied to the motor is described. The operation of such a conventional apparatus will be described.

First, the current detector 4 detects a motor current applied to the motor, and the voltage detector 3 detects a motor voltage applied to the motor.

At this time, the stroke estimator 5 applies the motor current, the motor voltage, and the motor parameter to the following equation to calculate a stroke estimate, and then applies the stroke estimate to the comparator 1.

[Equation]

Where R: resistance

        L: Inductance

        α: counter electromotive force

Accordingly, the comparator 1 compares the stroke estimate and the stroke command value and applies a difference signal to the stroke controller 2 according to which the stroke controller 2 varies the voltage applied to the motor. To control the stroke.

That is, as shown in Fig. 2, the stroke controller 2 reduces the motor applied voltage when the stroke command value is larger than the stroke estimate value, and increases the motor applied voltage when the stroke command value is smaller than the stroke estimate value.

As described above, the method of controlling the stroke of the reciprocating compressor has a problem in that the TDC fluctuates according to the load fluctuation and thus does not generate the same cooling force, and thus the cooling capacity fluctuates and the overall system efficiency is lowered.

The present invention has been made to solve the above problems, and by detecting the mid position of the current stroke and varying the stroke according to the mid position, the reciprocating to improve the system efficiency by maintaining a constant TDC regardless of the load It is an object of the present invention to provide an operation control apparatus and method for a compressor.

According to an aspect of the present invention, there is provided a reciprocating compressor comprising: stroke estimation means for calculating a stroke estimate using a voltage and a current applied to a motor and a motor parameter; Mid position calculating means for calculating a mid position with said stroke estimate; Stroke command value determining means for comparing the mid position with a previous mid position to determine a stroke command value by adding or subtracting a stroke command correction value according to the stroke command value; And a stroke control means for comparing the stroke command value with the stroke estimation value and controlling the stroke by varying the voltage applied to the motor according to the comparison result.

The present invention for achieving the above object comprises a first step of calculating a stroke estimate using the voltage and current and motor parameters applied to the motor; Calculating a mid position for a current stroke from the stroke estimate; A third step of correcting a stroke command value by comparing the mid position with a previous mid position; The stroke command value is compared with the stroke estimate value, and the fourth step of controlling the stroke by varying the voltage applied to the motor according to the comparison result.

Hereinafter, with reference to the accompanying drawings, the operation and effects of the operation control apparatus and method of the reciprocating compressor according to the present invention will be described in detail.

First, the present invention is based on the fact that the cooling capacity and the system efficiency are closer to the TDC rather than the stroke, and that the relation between the suction pressure and the mid position data is more stable than the relation between the suction pressure and the stroke as shown in FIG. It is to be noted that attention was paid.

Figure 3 is a block diagram showing the configuration of the operation control apparatus of the reciprocating compressor of the present invention, as shown therein a current detecting unit 50 for detecting a motor current applied to the motor; A voltage detector 40 detecting a motor voltage applied to the motor; A stroke estimator (60) for estimating a stroke based on the detected motor current, motor voltage and motor parameters; A mid position calculator 70 for calculating a mid position from the stroke estimate; A stroke command value determining unit (10) for comparing the mid position with the previous mid position to determine a stroke command value by adding or subtracting a stroke command correction value according to the stroke command value; A comparator 20 for comparing the stroke command value and the stroke estimate value and outputting a difference signal accordingly; In accordance with the difference signal, the voltage applied to the motor is configured by the stroke controller 30 to control the stroke.

FIG. 4 is a flowchart illustrating an operation control method of the reciprocating compressor according to the present invention, and a first process of calculating a stroke estimate using a voltage and a current applied to a motor and a motor parameter as shown in FIG. Calculating a mid position for a current stroke using the stroke estimate; A third step of correcting a stroke command value by comparing the mid position with a previous mid position; A fourth process of controlling the stroke by varying the voltage applied to the motor by comparing the stroke command value with the stroke estimate value, will be described.

First, the current detector 50 detects a motor current applied to the motor, and the voltage detector 40 detects a motor voltage applied to the motor.

At this time, the stroke estimator 60 applies the motor current, the motor voltage, and the motor parameter to the following equation to calculate a stroke estimate, and then applies the stroke estimate to the mid position calculation unit 70.

[Equation]

Where R: resistance

        L: Inductance

        α: counter electromotive force

6 is a schematic view showing the durability structure of the reciprocating compressor to which the present invention is applied.

Accordingly, the mid position calculation unit 70 calculates the mid position using the stroke estimation value, that is, the following equation.

[Equation]

Mid Position (M_P) =

Here, the mid position means the exact center of the TDC and the BDC, which means the middle value between the maximum and minimum values of the stroke, T means one cycle time of the stroke, and X is an estimate of the stroke (distance of the piston). At this time, the stroke command value determining unit 10 receives the mid position, compares it with the previous mid position, determines the stroke command value accordingly, and applies it to the comparator 20, that is, the current mid position is the previous mid position. If larger, the stroke command correction value is added to the current stroke command value to determine the stroke command value. If the current mid position is smaller than the previous mid position, the stroke command correction value is determined by subtracting the stroke command correction value to the current stroke command value.

Here, the stroke command correction value is a stroke size correction value necessary for keeping the TDC constant, and is set to an appropriate value by experiment. Accordingly, the comparator 20 estimates the stroke value and the stroke. The command value is compared and the difference signal corresponding thereto is applied to the stroke controller 30, whereby the stroke controller 30 controls the stroke by varying the voltage applied to the motor.

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That is, the stroke controller 30 decreases the motor applied voltage when the stroke command value is larger than the stroke estimate value, and increases the motor applied voltage when the stroke command value is smaller than the stroke estimate value.

In more detail, the present invention will be described with reference to Fig. 4, first, the motor voltage and the motor current are detected, and then the stork estimate is calculated using the detected motor voltage and the motor current and the motor parameters.

The mid position is then detected by the stroke estimate and the mid position is compared with the previous mid position.

As a result of the comparison, if the current mid position is larger than the previous mid position, the stroke command correction value is added to the stroke command value to determine the stroke command value. If the current mid position is smaller than the previous mid position, the stroke command value is subtracted from the stroke command value. Determine.

Then, the stroke command value is compared with the stroke estimate value to increase the motor applied voltage if the stroke command value is larger than the stroke estimate value, and reduce the motor applied voltage if the stroke command value is smaller than the stroke estimate value.

That is, the present invention detects the mid position of the current stroke and varies the stroke according to the mid position, thereby maintaining a constant TDC regardless of the load, thereby improving system efficiency. In this case, the TDC stands for Top Dead Center. It means the maximum value of the stroke, that is, the English notation of the top dead center of the piston in the reciprocating compressor, which physically means the position of the piston at the completion of the compression stroke of the piston. The abbreviation of the center means the minimum stroke value, that is, the English notation of the bottom dead center of the piston in the reciprocating compressor. The embodiments or examples are only intended to clarify the technical content of the present invention. Should not be narrowly interpreted as limited to these specific embodiments, it is possible to change various embodiments within the scope of the claims described in the following spirit of the invention.

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As described in detail above, the present invention detects the mid position of the current stroke and varies the stroke according to the mid position, thereby maintaining the constant TDC regardless of the load, thereby improving system efficiency.

1 is a block diagram showing a configuration for a driving control apparatus of a conventional reciprocating compressor.

2 is a flowchart illustrating an operation control method of a conventional reciprocating compressor.

Figure 3 is a block diagram showing the configuration of the operation control device of the reciprocating compressor of the present invention.

Figure 4 is an operation flowchart of the operation control method of the reciprocating compressor of the present invention.

Fig. 5 shows the relationship between stroke and suction pressure and mid position and suction pressure.

Figure 6 is a schematic diagram showing the structure of a device to which the operation control apparatus of the present invention reciprocating compressor is applied.

***** Description of the symbols for the main parts of the drawings *****

10: Stroke command value determining unit 20: Comparator

30: stroke controller 40: voltage detector

50: current detector 60: stroke estimator

70: mid position calculation unit

Claims (4)

In a reciprocating compressor, Stroke estimation means for calculating a stroke estimate using a voltage and a current applied to the motor and a motor parameter; Mid position calculating means for calculating a mid position with said stroke estimate; Stroke command value determining means for comparing the mid position with a previous mid position to determine a stroke command value by adding or subtracting a stroke command correction value according to the stroke command value; And stroke control means for comparing the stroke command value and the stroke estimate value and controlling the stroke by varying the voltage applied to the motor according to the comparison result. The stroke command value determining means according to claim 1, If the current mid position is larger than the previous mid position, the stroke command correction value is added to the current stroke command value to determine the stroke command value. And if the current mid position is smaller than the previous mid position, the stroke command value is determined by subtracting the stroke command correction value from the current stroke command value. Calculating a stroke estimate using a voltage and a current applied to the motor and a motor parameter; Calculating a mid position for a current stroke using the stroke estimate; A third step of correcting a stroke command value by comparing the mid position with a previous mid position; And comparing the stroke command value with the stroke estimation value and performing a fourth process of controlling the stroke by varying the voltage applied to the motor according to the comparison result. The method of claim 3, wherein the third process comprises:  A first step of determining a stroke command value by adding a stroke command correction value to the stroke command value if the current mid position is larger than the previous mid position; And a second step of subtracting the stroke command correction value from the stroke command value to determine the stroke command value if the current mid position is smaller than the previous mid position.